Pull type release control of electric apparatus

ABSTRACT

A device for setting an electric apparatus in permanent operation by exerting a momentary mechanical pull on a release rope characterized in that it comprises a pressure-type contact, mechanical means holding the push member of this pressure contact in its depressed or operative position when no traction is exerted on the release rope, and a bistable electronic switch connected between a source of electric power and the electric apparatus to be energized, said switch being so connected to said pressure contact that said switch is open as long as said push member is held in its depressed or operative position, and moved to its closed position when a tractive effort in excess of a predetermined threshold is exerted on said rope to enable said push member to resume its inoperative position.

United States Patent Inventors Henry Piazza Toulouse; Pierre Bach, Ferney Voltaire, both of, France Appl. No. 805,702 Filed Mar. 10, 1969 Patented Aug. 31, 1971 Assignee French State, represented by the Minister 01 Armed Forces Min'sterlal Delegation for Weapons, Technical Direction of Land Weapons, Manufacturing Workshop of Toulouse Paris, France Priority Mar. 15, 1968 France 143,898

PULL TYPE RELEASE CONTROL OF ELECTRIC APPARATUS 1 Claim, 8 Drawing Figs.

US. I 200! 161, 244/150 hit. (I H0111 17/16 Field ofSearch 307/116,

Primary Examiner-Robert K. Schaefer Assistant Examiner-William .1. Smith Attorneys-Robert E. Burns and Emmanuel J. Lobato ABSTRACT: A device for setting an electric apparatus in permanent operation by exerting a momentary mechanical pull on a release rope characterized in that it comprises a pressuretype contact, mechanical means holding the push member of this pressure contact in its depressed or operative position when no traction is exerted on the release rope, and a bistable electronic switch connected between a source of electric power and the electric apparatus to be energized, said switch being so connected to said pressure contact that said switch is open as long as said push member is held in its depressed or operative position, and moved to its closed position when a tractive effort in excess of a predetermined threshold is exerted on said rope to enable said push member to resume its inoperative position.

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' sum u or 4 PULL TYPE RELEASE CONTROL OF ELECTRIC APPARATUS BACKGROUND OF THE INVENTION The present invention relates to a device for releasing an electric apparatus for permanent operation by means of a mo mentary mechanical pull, during a given mechanical process, notably, in the case of a parachuted apparatus, during one of the parachute opening steps.

Hitherto known pull-type release devices, usually based on the principle of tearing a part such as a safety pin attached to the traction rope or like element, are seldom reusable since the part thus torn off during the release phase is either damaged or lost. Moreover, mainly in the case of parachuted material or equipment, untimely releases may take place as a consequence of accidental tractive efforts exerted on the release rope during packaging, aircraft-holding loading operations, or when jettisoning the load from the aircraft.

SUMMARY OF THE INVENTION It is the essential object of this invention to avoid these inconveniences by providing a device of particularly simple design.

To ,this end, the device according to the present invention for setting an electric'apparatus in permanent operation by exerting a momentary mechanical pull on the release rope is characterized in that it comprises a pressure-type contact, mechanical means holding the push member of this pressure contact in its depressed or operative position when no traction is exerted on the release rope, and a bistable electronic switch connected between a source of electric power and the electric apparatus to be energized, said switch being so connected to said pressure contact that said switch is open as long as said push member is held in its depressed or operative position, and moved to its closed position when a tractive effort in excess of a predetermined threshold is exerted on said rope to enable said push member to resume its inoperative position.

The device according to the present invention is advantageous in that it constitutes a compact unit of which all the component elements remain in their original relationship and integral after the release of the electric apparatus controlled thereby.

Another advantageous feature characterizing the device of this invention, which derives from the above-defined advantage,v is that a same device can be used a great number of times without producing any change in its operating characteristics.

Besides, means are provided for preventing any untimely release of the device in case of accidental pulling of the release rope, for example during the handling or maneuvers preceding the jettisoning from an aircraft.

The device according to the present invention is adapted for use in the automatic release of a great number of parachuted equipments and apparatus such as a low-altitude altimetric sounding device, or a decelerometric release device. It may also be used to advantage as an alarm device adapted to start the operation of signal means when the mechanical traction exerted on a rope exceeds a predetermined value.

BRIEF DESCRIPTION OF THE DRAWING Various forms of embodiment of the present invention will now be described by way of example with reference to the attached drawings, it being understood that the structures shown and described herein should not be construed as limiting the invention since various modifications and variations may be brought thereto without departing from the spirit and scope of the invention as set forth in the appended claims. In the drawings:

FIG. 1 is a diagrammatic sectional view of a mechanical device for releasing the operation of an electric apparatus (not shown),- with its associated pressure-type reversing contact or switch;-

FIG. 2 is a diagram showing the force vs. compression or elongation (set) of the resilient member of the mechanical device shown in FIG. 1;

FIG. 3 is a diagrammatic sectional view showingv a modified form of embodiment of the release device of this invention;

FIG. 4 is a diagram illustrating the force vs. compression or elongation (set) of the resilient member of the mechanical device shown in FIG. 3;

FIG. 5 is a wiring diagram of the electrical circuit associated with the device according to this invention;

FIG. 6 is a wiring diagram concerning a modified form of embodiment; Y 7 FIG. 7 is a diagrammatic sectional view showing a modified form. of embodiment of the device of this invention;

FIG. 8 is a diagrammatic section showing another modification of the device constituting the subject-matter of this inven- DESCRIPTION OF THE PREFERRED EMBODIMENT v The device illustrated in FIG. 1 comprises a resilient member 1 subjected to a constant elongation prestress between a movable member 2 rigid with a pull member 3, such as a traction rope or the like, and the frame or fixed structure 4 of an apparatus. The movable member 2 acts upon a push member 5 of an electric reversing switch 8 comprising three terminals 6, 7 and 9.

The force vs. elongation characteristic of the resilient member 1 illustrated in FIG. 2 affords a clearer understanding of the mode of operation of the release mechanism. The resilient member 1, when isolated and in the absence of any external force, has an inherent length l f'lhis member is inserted between the movable member 2 and the frame structure 4 so that its length is then 1 greater than 31 The stress F thus exerted by member 1 through the medium of member 2 against push member 5 will keep the latter in its depressed condition; in this case the terminals 6 and 7 of reversing switch 8 are interconnected and terminals 7 and 9 are disconnected or isolated from each other.

When the rope 3 is pulled the gradual elongation of the resilient member 1 permits the upward movement of push member 5; when the stress F corresponding to the release threshold is attained the length of resilient member 1 has a value 1 I (elongation A and the push member is fully released. Thus, terminals 6 and 7 which were constantly connected in the inoperative condition, i.e. when no pull was exerted on member 3, are thus separated and terminal 9 is connected to terminal 7. When the stress exceeds the release threshold the movable member 2 moves away from push member 5 and the elongation of member I isthen limited by a stop 4a.

In the device illustrated in FIG. 3 the resilient member I is constantly compression-stressed between the movable member 2 to which the pull rope 3 is attached and the stop 4a rigid with the frame structure of the apparatus.

FIG. 4 illustrates the force vs. compression of the resilient member 1 of FIG. 3; when this resilient member I is unstressed and isolated, its length is 1 when inserted and therefore prestressed between the movable member 2 and the stop member 4a rigid with the frame structure, its length is l 1 and its force F 1 then exerted through the medium of member 2 against push member 5 is sufficient for holding this member 5 in its depressed condition. When the rope or like pull member 3 is pulled upwards the push member 5 is gradually released by compressing the resilient member 1, the release threshold F corresponding to a complete release of said push member. The internal electrical connection between terminals 6 and 7 is then broken and terminals 7 and 9 are now interconnected.

These mechanical devices cannot control directly the permanent operation of an electric apparatus; in fact, any evolution to the tractive force within or below this release threshold will cut off the supply of energizing current to said apparatus.

parting a permanent character to the operation started thereby. The device contemplated for this purpose comprises a thyristor, whether of the positive or negative control type.

FIGS. 5 and 6 illustrate two different forms of embodiment of the electronic subassembly, these forms of embodiment differing according to the type of control circuit of said thyristor.

In the arrangement illustrated in FIG. 5, the three terminals 6, 7 and 9 of the pressure-type reversing switch 8 are utilized. A positive-control thyristor 10 is inserted in a series electric circuit comprising a source of power 11 and the apparatus 12 to be energized. When no tractive effort is exerted on the rope 3 or if this effort is inferior to the above-defined release threshold, terminals 6 and 7 of reversing switch 8 are interconnected, thus short-circuiting the control electrode 13 and cathode 14 of said thyristor and keeping the latter blocked. When the tractive effort exceeds the release threshold the push member 3 is released and causes terminals 7 and 9 to be interconnected. Thus the control electrode 13 is brought via a resistor 15 having a value R to the positive voltage of the power source and the now conducting thyristor 10 will energize the controlled apparatus 12; under these conditions the conductivity of thyristor 10 is irreversible and when the push member resumes its depressed position the energization of apparatus 12 is not discontinued.

The modified form of embodiment illustrated in FIG. 6 utilizes only two terminals of the pressure-actuated reversing switch 8 in its control circuit. When no tractive effort is exerted on pull member 3, or when this effort is lower than the release threshold, terminals 6 and 7 are interconnected. Since terminal 9 is not connected, a resistor 16 having a value R, and inserted between the control electrode 13 and the cathode 14 of thyristor 10 restores the voltage of electrode 13 to the value of cathode 14, thus preventing the thyristor 10 from conducting. When the tractive effort exceeds the release threshold value, terminals 7 and 9 are interconnected. Under these conditions, the control electrode 13 is connected via resistor 13 to the positive terminal of the source of power 11, thus causing the thyristor 10 to become conductive and nonreversibly energize the controlled apparatus 12.

In order to afford a clearer understanding of the invention two complete control equipments operating according to the invention will now be described with reference to FIGS. 7 and 8 of the drawings.

Referring first to FIG. 7, a first equipment according to this invention is illustrated which comprises a substantially parallelepipedic or cylindrical case 24 provided with an internal transverse partition 25 to which the reversingswitch 8 is secured. This partition 25 divides the inner space of case 24 into two chambers 26 and 27 receiving the former the mechanical components and the latter the electric and electronic components of the device. Thus, the upper chamber 26 encloses a coin compression spring 1a which is tensionprestressed between a movable plate 24 and the aforesaid transverse partition 25 to which it is anchored by means of retaining in-tumed flanges 17 or like means. The top wall 18 of case 24 has an orifice 18a of substantially chain or deckpipe configuration whereby the pull rope 3 emerging therethrough can be pulled in all directions while forming a maximum angle a with the axis of the apparatus. The central portion 19 of this top wall 18, which is concentric to said orifice 18a, acts as a stop for limiting the permissible stroke of said movable member 2a. The associated electronic device similar to the one illustrated in FIG. 5 is housed in the lower chamber 27 of case 24. The source of electric power 11 and the controlled apparatus 12 are electrically connected to the release device by means of flexible cables provided with connectors 20 and 21, as shown.

The device illustrated in FIG. 8 differs from the preceding one by the use of acompression prestressed coil spring lb disposed between an anchoring collar 23 formed in the upper wall of case 24 about and concentric to an aperture 28 and the movable member 2b. This movable member consisting of a lever projecting through said aperture 28 to the outside and formed with an integral spherical body acting as a universal swivel member permits of pulling said levers in all directions up to an angle a with respect to the axis of the device. The electronic unit incorporated in the lower chamber of the device is the one illustrated in FIG. 6. This alternate form of embodiment of the device is particularly suitable for releasing, or starting the operation of, an apparatus jettisoned by parachuting; in fact, during the jettisoning steps, whether outside the aircraft or during the handling operations in the aircraft hold, an accidental traction exerted on the pull rope which is sufficient for releasing the apparatus may occur. To avoid this inconvenience the pull member 3 is connected by means of a short rope 22 to the frame structure or case 24 of the device, whereby any preliminary traction will first break the short rope 22, thus protecting the device and therefore the apparatus controlled thereby against any premature release.

Of course, the above description and attached drawings refer only to exemplary forms of embodiment of the present invention, and as already emphasized various modifications may be brought thereto without departing from the spirit and scope of the invention. Thus, notably, any desired combination of the mechanical elements of FIGS. 1 and 3 with the electronic means of FIGS. 5 and 6 may advantageously be contemplated. 1

What we claim is:

1. A device for closing permanently the supply circuit of an electric apparatus by a single, transient, mechanical pull on a release rope, comprising in combination a bistable electronic switch inserted in said supply circuit and having a control circuit, a monostable push-type mechanical switch having a push member, said mechanical switch being mounted on one wall of a casing and being electrically inserted in the control circuit of said electronic switch, a lever having at its inner end a spherical portion acting as a swivel member, said lever being connected at its outer end to said release rope, and reacting with its inner end on the push member of said mechanical switch, and a spring member disposed between said lever and one wall of said casing, for continuously biasing the pushmember of said mechanical, monostable switch in its depressed, unstable position, whereby said push member biasing is counteracted by a transient pull on said release rope, and said mechanical switch is thereby transiently actuated. 

1. A device for closing permanently the supply circuit of an electric apparatus by a single, transient, mechanical pull on a release rope, comprising in combination a bistable electronic switch inserted in said supply circuit and having a control circuit, a monostable push-type mechanical switch having a push member, said mechanical switch being mounted on one wall of a casing and being electrically inserted in the control circuit of said electronic switch, a lever having at its inner end a spherical portion acting as a swivel member, said lever being connected at its outer end to said release rope, and reacting with its inner end on the push member of said mechanical switch, and a sprIng member disposed between said lever and one wall of said casing, for continuously biasing the push-member of said mechanical, monostable switch in its depressed, unstable position, whereby said push member biasing is counteracted by a transient pull on said release rope, and said mechanical switch is thereby transiently actuated. 